How to check the extension of a Java 7 Path

问题

I'd like to check if a Path (introduced in Java 7) ends with a certain extension. I tried the endsWith() method like so:

Path path = Paths.get("foo/bar.java")
if (path.endsWith(".java")){
    //Do stuff
}

However, this doesn't seem to work because path.endsWith(".java") returns false. It seems the endsWith() method only returns true if there is a complete match for everything after the final directory separator (e.g. bar.java), which isn't practical for me.

So how can I check the file extension of a Path?

回答1:

Java NIO's PathMatcher provides FileSystem.getPathMatcher(String syntaxAndPattern):

PathMatcher matcher = FileSystems.getDefault().getPathMatcher("glob:*.java");

Path filename = ...;
if (matcher.matches(filename)) {
    System.out.println(filename);
}

See the Finding Files tutorial for details.

回答2:

The Path class does not have a notion of "extension", probably because the file system itself does not have it. Which is why you need to check its String representation and see if it ends with the ~~four~~ five character string .java. Note that you need a different comparison than simple endsWith if you want to cover mixed case, such as ".JAVA" and ".Java":

path.toString().toLowerCase().endsWith(".java");

回答3:

Simple solution:

if( path.toString().endsWith(".java") ) //Do something

You have to be carefull, when using the Path.endsWith method. As you stated, the method will return true only if it matches with a subelement of your Path object. For example:

Path p = Paths.get("C:/Users/Public/Mycode/HelloWorld.java");
System.out.println(p.endsWith(".java")); // false
System.out.println(p.endsWith("HelloWorld.java")); // true

回答4:

There is no way to do this directly on the Path object itself.

There are two options I can see:

Convert the Path to a File and call endsWith on the String returned by File.getName()
Call toString on the Path and call endsWith on that String.

来源：https://stackoverflow.com/questions/20531247/how-to-check-the-extension-of-a-java-7-path

标签

java

path

java-7